In automatic programming for creating NC data using an automatic programming language such as APT or FAPT, (a) a part program based on the automatic programming language is created by defining points, straight lines and circular arcs using simple symbols (this is referred to as "figure definition"), and then defining a tool path using the defined points, straight lines and circular arcs (referred to as "motion statement definition"), and (b) the part program based on the automatic programming language is subsequently converted, by using an NC data output table, into NC data comprising NC data (EIA codes or ISO codes) in a format capable of being executed by an NC unit. The NC data output table stores NC data output formats for various commands, such as a linear interpolation command, circular interpolation command and coordinate system setting command. By referring to the table, the part program is converted into NC data in the format to be executed and is then delivered as an output. For example, the following command format for linear interpolation is stored in the table to deal with linear interpolation:
G90/G91 PA1 G00/G01 PA1 Xx PA1 Yy PA1 Ff PA1 EOB PA1 G90/G91 PA1 G02/G03 PA1 Xx PA1 Yy PA1 Jj PA1 EOB
and the following command format for circular interpolation is stored in the table to deal with circular interpolation:
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There are cases where it is desired to have machining, which is similar to that performed by a first numerically controlled machine tool already in operation, executed by a second numerically controlled machine tool of a type different from that of the first numerically controlled machine tool. If the NC data formats for both of the numerically controlled machine tools are the same when the above is the case, then the second numerically controlled machine tool can be controlled using the NC data of the first numerically controlled machine tool as it is.
If the NC data formats of the two numerically controlled machine tools are different, on the other hand, the NC data output table of the automatic programming apparatus is modified for the sake of the second numerically controlled machine tool, the NC data for the second numerically controlled machine tool are created using the already prepared part program based on the automatic programming language, and the second numerically controlled machine tool is controlled in accordance with these NC data.
However, the conventional method of dealing with NC data formats that differ is a troublesome one since the NC data output table of the automatic programming apparatus must be modified. In addition, there are cases where the part program based on the automatic programming language no longer exists. In such case the conventional method cannot be applied and the NC data form must be modified by a manual operation.
Accordingly, an object of the present invention is to provide an NC data modification method through which NC data having an executable format can be automatically changed to NC data of another type without using a part program based on automatic programming language.